There is a lot of talk on this site about pods, and air boxes and air flow and such, and since most of it seems to come from newbies who maybe haven't seen stuff like this I thought it might be nice to talk about something other than pods and carb tuning and blah, blah, blah.
So this is a Henry Abe AirBox:
Actually it is a bit of a misnomer because Henry Abe wasn't the only company to make them, Santee, Ness, AEE, all offered similar products and designs. The basic premise was to have something cooler looking than an airbox but worked better than a generic pod filter.
Over the years I have collected a few of these where I have found them and decided to rebuild one for use on the CB750F I have a thread about, and also another to sell. But I thought it might be good to go over what makes these tick.
So here you see the basics. On the far right is an assembled heavily road worn cb750 unit. Next to that are the airbox specific rubbers, the carb side mounting plate, the inner filter mesh, the outer filter mesh, followed by the outward facing plate. Below you see the Z bracket that is used to keep the filter from collapsing under vacucum and one of the two bolts that holds the unit together. Above is a piece of Unifilter foam, to the far left is a stock cb750 intake rubber, and in the tray is all the hardware I am too lazy to spread out like the clamps and the other body bolt.
Please forgive this pic as I didn't realize the focus was misadjusted until I uploaded it this morning, I'll fix it at some point:
On the left is a stock cb750 intake rubber, on the right is the Henry Abe airbox rubber. A couple things to note:
1) the cb750 one is much longer and has a short external mounting flange followed by a large amount of the velocity stack inside the airbox. Conversely the henry abe specific one has a long external mounting flange but is much shorter overall in height. Very little of the stack is in the airbox to allow for room to suck in air.
2) both have a velocity stack shape but the HA's rubber has a more open bellmouth with a longer taper.
3) the flange where it goes into the body of the filter is slightly bigger. I can from experience tell you that you can use a stock cb750 rubber in an HA airbox but you need to seal the flange with some silicone sealant to prevent air leaks, and you will have to cut down the velocity stack portion as it is almost up against the inside of the front plate.
The original filter material was likely a foam of some type and sheet Uni Filter foam is easy and cheap to come by. Here I cut the filter sheet into strips for installation:
This filter will have to be oiled. perioically and replaced when it becomes brittle.
not all the rubbers are in good shape:
these aren't reproduced so you have to use what you can. I find that black liquid electrical tape helps seal up any missing chunks and some regular black electrical tape around the outside helps seal it all together. Since these do not have to pass fuel and will mostly sit on the outside of the carb I am not concerned about any repairs. any raised dried liquid tape can be trimmed with a razor blade.
Here is a close up of the actual breathable outside element:
now I know what you are thinking - those holes look kinda small. I think it too. The reality is that this piece is structural to the airbox in that the two outer plates clamp firmly against it. You can drill these but I caution you that if you drill too big you can weaken the plate and the airbox will crush in on itself when you go to tighten it up. There are some other tricks you can do and we will talk about them in part 2: modifying.
Installing the filter:
you take the two strips of foam you cut and lay them inside the outer element. Make sure they are well oiled as per UNI's instructions.
then you lay the inside reinforcement element so that your engine does not suck in a bunch of foam.
To be continued.....
So this is a Henry Abe AirBox:
Actually it is a bit of a misnomer because Henry Abe wasn't the only company to make them, Santee, Ness, AEE, all offered similar products and designs. The basic premise was to have something cooler looking than an airbox but worked better than a generic pod filter.
Over the years I have collected a few of these where I have found them and decided to rebuild one for use on the CB750F I have a thread about, and also another to sell. But I thought it might be good to go over what makes these tick.
So here you see the basics. On the far right is an assembled heavily road worn cb750 unit. Next to that are the airbox specific rubbers, the carb side mounting plate, the inner filter mesh, the outer filter mesh, followed by the outward facing plate. Below you see the Z bracket that is used to keep the filter from collapsing under vacucum and one of the two bolts that holds the unit together. Above is a piece of Unifilter foam, to the far left is a stock cb750 intake rubber, and in the tray is all the hardware I am too lazy to spread out like the clamps and the other body bolt.
Please forgive this pic as I didn't realize the focus was misadjusted until I uploaded it this morning, I'll fix it at some point:
On the left is a stock cb750 intake rubber, on the right is the Henry Abe airbox rubber. A couple things to note:
1) the cb750 one is much longer and has a short external mounting flange followed by a large amount of the velocity stack inside the airbox. Conversely the henry abe specific one has a long external mounting flange but is much shorter overall in height. Very little of the stack is in the airbox to allow for room to suck in air.
2) both have a velocity stack shape but the HA's rubber has a more open bellmouth with a longer taper.
3) the flange where it goes into the body of the filter is slightly bigger. I can from experience tell you that you can use a stock cb750 rubber in an HA airbox but you need to seal the flange with some silicone sealant to prevent air leaks, and you will have to cut down the velocity stack portion as it is almost up against the inside of the front plate.
The original filter material was likely a foam of some type and sheet Uni Filter foam is easy and cheap to come by. Here I cut the filter sheet into strips for installation:
This filter will have to be oiled. perioically and replaced when it becomes brittle.
not all the rubbers are in good shape:
these aren't reproduced so you have to use what you can. I find that black liquid electrical tape helps seal up any missing chunks and some regular black electrical tape around the outside helps seal it all together. Since these do not have to pass fuel and will mostly sit on the outside of the carb I am not concerned about any repairs. any raised dried liquid tape can be trimmed with a razor blade.
Here is a close up of the actual breathable outside element:
now I know what you are thinking - those holes look kinda small. I think it too. The reality is that this piece is structural to the airbox in that the two outer plates clamp firmly against it. You can drill these but I caution you that if you drill too big you can weaken the plate and the airbox will crush in on itself when you go to tighten it up. There are some other tricks you can do and we will talk about them in part 2: modifying.
Installing the filter:
you take the two strips of foam you cut and lay them inside the outer element. Make sure they are well oiled as per UNI's instructions.
then you lay the inside reinforcement element so that your engine does not suck in a bunch of foam.
To be continued.....